Stem cells are believed to be a promising source for replacement therapies in diseases of the nervous system. Endogenous adult stem cells can be also activated to regenerate and re¬pair damaged tissues. In order to utilize their capacities, it is important to understand the underlying mechanism of their plasticity and how the gene expression will be al¬tered to adopt new cell fates. We have previously identified that that TLX (tail-less homologue, also named NR2E1) orphan receptor induces the reprogramming factor Oct4 for self-renewal of neural stem cells (Chavali et al, 2011) and TLX stabilizes HIF-a by preventing deg¬radation of pVHL in neuroblastoma even in normoxia (Zeng et al, 2012). Moreover, we found that that TLX is enriched in tumor-initiating cell population where TLX transcriptionally induces angiogenesis, invasion, and migration stimula¬tory molecules (VEGF, and matrix metallo¬proteinases 2 and 9)(Chavali, Saini et al, 2013).
Our first aim in the current project is to characterise the mechanism of the TLX as a self-renewing gene and its roles for neurogenesis. Secondly, we examine the involvement of TLX in so-called tu¬mor-initiating cells (TIC) in the nervous system, focusing on angiogenesis and migration. Thirdly, we examine the signal interference between the growth inhibitor TGF-β and TLX pathways, as a mechanism for tumor resistance against TGF-β. A similar interference exists between the apoptosis regulating kinase (ASK1) and TLX, which explains the anti-apoptotic role of TLX in tumors.
Several factors suggest TLX dysfunction to be associated with cognitive impairment in experiments on mice. Thus, we continue the translational project initiated in collaboration with clinicians to identify biomarkers of diagnostic and therapeutic interest for bipolar disorder, the most severe type of depression interfoliated with manic episodes, having a strong hereditary component. In this pro¬ject, we study (1) perturbed signalling pathways by drug stimulation of adipocytes cultured from subcutaneous biopsies, as well as (2) pathological alterations, by creating induced pluripotent stem cells (iPSC) from the adipocyte cultures. By comparing the profiles of iPSC-to-nerve cell differentiation by RNA sequencing and methylation analysis in patients and controls, we will be able to phenocopy the possi¬ble developmental deficiency inherent in the disease. Obtained nerve cells will be examined as for their phe¬notypes and functions by electrophysiology.
We use various molecular biology techniques in cultured mammalian cells as well as genetically mutated mice to define mechanisms and in search for therapy targets in the nervous system tumors. Furthermore, we apply various microscopy techniques by using High-Content and Confocal microscopes to monitor the dynamics of subcellular structures in order to understand the cellular mechanisms. For the bipolar study, iPS lines are currently produced at our partner Cellectus.
Keiko Funa, MD, PhD, Professor
Dzeneta Vizlin Hodzic, PhD, postdoc
Qiwei Zhai, MD